The invention relates to a dampening device for offset lithographic printing machines and in particular to a device by which a dampening fluid is atomized and applied as a finely dispersed spray or mist to a transferroll, drum or form roll comprising part of a fluid distributing means for subsequent movement to a plate cylinder.
Various dampening devices for lithographic and offset printing machines have been used in the past. In all such devices, there is the requirement that the dampening fluid, which may take the form of water, be evenly spread and finely distributed in the form of a fine film onto a lithographic stone or offset lithographic printing plate. Various devices have been used in the past in an attempt to insure that the dampening fluid film applied to the surface of the printing plate was even and of the same distribution across the width of the plate. Such devices have utilized spray guns, electrostatic charging of moving droplets of dampening fluid, or rotating brush rollers where the fibers of the brush are flicked to throw droplets of fluid onto a transfer roll. The prior art devices have not been completely successful in that the application of the fluid to the plate and the proper proportion of the fluid to the printing ink has often been affected by different speeds of the printing machine. Further, the prior art devices often caused ink streaking due to the inability to break the water up into sufficiently small droplets or mist such that it could be applied evenly onto the printing plate. It is therefore an object of our invention to provide for a dampening device which may provide an evenly distributed and consistent amount of dampening fluid to a printing plate cylinder notwithstanding the speed at which the press may operate.